The invention relates to inhibiting damage to donor tissue in a device in contact with a host tissue.
Transplantation of donor tissue into a recipient can be used to treat a wide variety of disorders, including heart disease, neoplastic disease, and endocrine disease. The clinical application of transplantation-based therapies are, however, limited by several factors. These factors include immune rejection of transplanted allogeneic or xenogeneic tissue by the transplant recipient, a shortage of allogeneic donor-tissue, and donor-propagated immune attack of recipient tissue (graft-versus-host-disease).
Immune rejection of transplanted donor-tissue can be the most serious barrier to more widespread availability of the benefits of transplantation-based therapies. Implantation of allogeneic or xenogeneic donor-tissue into an immunocompetent recipient generally results in a vigorous and destructive immune response directed against the donor-graft. Efforts to prevent immune-based destruction of donor tissue have generally fallen into two categories. In one approach, efforts have been directed to moderating the recipient""s immune response, e.g., by the induction of specific immunological tolerance to transplanted tissue, or much more frequently, by the administration of broad-spectrum immune suppressants, e.g., cyclosporin. In the other major approach, efforts to prolong the acceptance of a donor-graft have been directed to rendering the donor-graft less susceptible to attack, e.g., by immunoisolating the donor-tissue by encapsulating it in a way which minimizes contact of elements of the recipient""s immune system with the encapsulated donor tissue.
Immunoisolation is particularly attractive for the treatment of endocrine disorders or in hormone or enzyme replacement therapies. For example, the implantation of immunoisolated pancreatic islet cells can be used to restore glucose-responsive insulin function in a diabetic recipient. Islets can be placed in a mechanical enclosure, or can be coated with a material, which allows relatively free diffusion of glucose, insulin, nutrients, and cellular waste products but which is impervious to components of the recipient""s immune system.
A variety of devices can be used to contain or cloak a source of a therapeutic substance, often cells, which source provides the substance to a host or recipient subject. Such devices include implantable devices, of both the diffusion and perfusion types, and extra corporeal devices, e.g., those through which blood of the host or recipient is passed. In such devices, host molecules can attack the source of the therapeutic substance and impair the function of the device. Semipermiable components are used to inhibit the ability of host molecules to enter the device and attack the source of therapeutic substance. The inventors have discovered that release, by the device, of components of the source of therapeutic substance, can stimulate a host response against the device and that capture of such components, prior to release or prior to becoming available to the immune system of the host, can improve the performance of the device, e.g., by extending its useful lifetime.
The inventors have discovered that the inclusion in an implantable device of a capture agent, e.g., an antibody directed against an antigen of the source of a therapeutic substance, which sequesters therapeutic source molecules, can improve the performance of the device, e.g., by extending its useful lifetime.
Accordingly, the invention features, an implantable device which includes a source of a therapeutic substance, e.g., an islet, and a capture agent, e.g., an antibody which binds a component of the therapeutic substance, disposed within or on a semipermeable component. The capture agents are preferably immobilized within the interior of the device or on its surface or are in a different compartment than the source of a therapeutic substance, or otherwise immobilized to keep it from contacting the source of a therapeutic substance. The capture agent can, e.g., coupled to a substrate, e.g., an inert bead in a compartment of the microreactor, or can be coupled to the surface of the microreactor, or to the surface of a component of the microreactor.
In preferred embodiments, the capture agent is an antibody or antibody fragment, even more preferably, the capture agent is an antibody or antibody fragment which binds an antigen or epitope other than the therapeutic substance released by the source. In an even more preferred embodiment, the antibody or antibody fragment is directed against an antigen which is an MHC class I, an MHC class II, an SLA class I, or an SLA class II antigen. In another preferred embodiment, the antibody or antibody fragment is a human antibody, a humanized antibody, an antibody which is engineered to minimize host response, or an engineered binding protein of a parental protein which is preferably of human origin.
In preferred embodiments, the implantable device includes a cell or tissue. The cell or tissue can be autologous, allogeneic, or xenogeneic, with regard to the subject. A xenogeneic cell or tissue can be from a species which is concordant or discordant with the subject. The cell or tissue can be from the subject, but if it is from the subject, it is preferably genetically engineered to express a substance not normally expressed by or on that cell or tissue.
In preferred embodiments, the cell or tissue is from a dog, pig, goat, rabbit, horse, cow, or sheep, or a non-human primate species.
In preferred embodiments, the cell is a pancreatic islet cell. In preferred embodiments, the pancreatic islet is from a dog, pig, goat, rabbit goat, horse, cow, sheep, or a non-human primate. In particularly preferred embodiments, the pancreatic islet is from a pig. In preferred embodiments, the pancreatic islet is from a human other than the subject.
In preferred embodiments, the cell or tissue is genetically engineered.
The cell or tissue can be from the pancreas, adrenal gland, brain, kidney, liver, thymus parathyroid or thyroid. In a preferred embodiment, the cell is a cultured cell. In a preferred embodiment, the cell is from a primary culture. In a preferred embodiment, the cell has been treated with a cytokine or a growth factor.
In preferred embodiments, the cell is an immortalized cell; the cell is a blood cell; the cell or tissue is a fetal; the cell is a skin, astroglial, or myoblast cell.
In preferred embodiments, the source of a therapeutic substance (and preferably the capture agent) is immunoisolated from the host, e.g., it is isolated from contact with one or more host immune components, e.g., antibodies or components of the complement system.
In preferred embodiments, the implantable device is a perfusion device, e.g., devices through which the flow of blood is directed, e.g., intravascular devices, as e.g., in an arterial or venous shunt.
In preferred embodiments, the device can be a microcapsule or a macrocapsular device, e.g., a hollow fiber, a membrane chamber, or other device which separates the source of a therapeutic substance (and preferably the capture agent) from the host by an artificial semi-permeable barrier.
In preferred embodiments, the device serves to physically contain the source of a therapeutic substance, e.g., donor cells or tissues, (and preferably the capture agent), keeping them in a contained location, at least temporarily separated from the implantation site or tissues of the host.
In preferred embodiments, the device is a microcapsule or macrocapsule. It can include a gel member, e.g., a shape-retaining gel member, in which a source of a therapeutic substance, e.g., a cell or tissue, is embedded. The gel can be a hydrogel. In preferred embodiments, the hydrogel includes agarose, agar, collagen, polyethylene glycol (PEG), polyethylene oxide (PEO), or alginate. The agarose or alginate can have a high number of guluronic acid or a high number of mannuronic acid monomers. The microcapsule or macrocapsule can include a semipermeable membrane or coating, e.g., a semipermeable coating which surrounds a gel component, e.g. a gel core in which a cell or tissue is embedded. The semipermeable membrane can include a polymer, e.g., a positively charged polymer. By way of example, the positively charged polymer can be a polyamino acid. In preferred embodiments, the positively charged polymer includes lysine or ornithine. In a particularly preferred embodiment, the positively charged polymer is polylysine or another polymer of one or more positively charged amino acids. In preferred embodiments, the coating can include chitosan.
In another aspect, the invention features, a composite microreactor which includes:
(a) one, or a plurality, of an internal particle which includes:
(i) a source of a therapeutic substance, e.g., an islet;
(ii) an internal particle matrix, e.g., a gel core or a solid particle, which contacts the source;
(iii) (optionally) an internal semipermeable particle coating enclosing the internal particle matrix; and
(b) a super matrix, e.g., a gel super matrix, in which the internal particle (or particles) is embedded; and
(c) (optionally) an outer semipermeable coating enclosing the super matrix, the composite microreactor preferably providing a molecular weight cutoff that prevents molecules larger than about 400,000 daltons from coming into contact with the source.
The composite microreactor includes one or more capture agents. The capture agent should be in a different compartment than the source of a therapeutic substance or otherwise immobilized to keep it from contacting the source of a therapeutic substance. The capture agent can, e.g., be coupled to the surface of a component or the microreactor.
In preferred embodiments, the capture agent is an antibody or antibody fragment, even more preferably, the capture agent is an antibody or antibody fragment which binds an antigen or epitope other than the therapeutic substance released by the source. In an even more preferred embodiment, the antibody or antibody fragment is directed against an antigen which is an MHC class I, an MHC class II, an SLA class I, or an SLA class II antigen. In another preferred embodiment, the antibody or antibody fragment is a human antibody, a humanized antibody, an antibody which is engineered to minimize host response, or an engineered binding protein of a parental protein which is preferably of human origin.
In preferred embodiments, a capture agent, e.g., an antibody which binds antigens or epitopes other than the therapeutic substance released by the source, is disposed within one or more of an internal particle or the super matrix.
In preferred embodiments, one compartment, e.g., an internal particle, can include a first capture agent and a second compartment, e.g., a second internal particle, or the super matrix can include a second capture agent.
A compartment can include two or more capture agents. A capture agent can be included in more than one compartment.
In preferred embodiments an internal particle is coated with the three-part composite layer described herein.
In another aspect, the invention features, a double composite microreactor which includes:
(1) one, or a plurality, of an internal particle which includes:
(a) a source of a therapeutic substance, e.g., an islet;
(b) an internal particle matrix which contacts the source; and
(c) (optionally) an internal particle semipermeable coating enclosing the first internal particle matrix;
(2) one, or a plurality, of a particle which includes:
(a) the internal particle or particles of (1)
(b) a particle matrix in which the internal particle (or internal particles) is embedded; and
(c) (optionally) a particle semipermeable coating enclosing the particle;
(3) a super matrix in which the particle (or particles) of (2) is embedded; and
(4) (optionally) a super matrix or outer semipermeable coating, e.g., of polylysine enclosing the super matrix.
The composite microreactor includes one or more capture agents. The capture agents should be in a different compartment than the source of a therapeutic substance, or otherwise immobilized to keep it from contacting the source of a therapeutic substance.
In preferred embodiments, the capture agent is an antibody or antibody fragment, even more preferably, the capture agent is an antibody or antibody fragment which binds an antigen or epitope other than the therapeutic substance released by the source. In an even more preferred embodiment, the antibody or antibody fragment is directed against an antigen which is an MHC class I, an MHC class II, an SLA class I, or an SLA class II antigen. In another preferred embodiment, the antibody or antibody fragment is a human antibody, a humanized antibody, an antibody which is engineered to minimize host response, or an engineered binding protein of a parental protein which is preferably of human origin.
In preferred embodiments, a capture agent, e.g., an antibody which binds antigens or epitopes other than the therapeutic substance released by the source, is disposed within one or more of an internal particle, a particle, or the super matrix.
A compartment can include two or more capture agents.
In a preferred embodiment, one compartment, e.g., an internal particle, can include a first capture agent and a second compartment, e.g., a second internal particle, or a particle, or the super matrix, can include a second capture agent.
A capture agent can be included in more than one compartment.
In preferred embodiments, an internal particle is coated with the three-part composite layer described herein; a particle is coated with the three-part composite layer described herein; an internal particle and a particle are coated with the three-part composite layer described herein; an internal particle does not include the three-part layer but a particle is coated with the three-part composite layer described herein.
In another aspect, the invention features, a composite microreactor which includes:
(a) one, or a plurality, of an internal particle which includes:
(i) pig islet cells as a source of a therapeutic substance;
(ii) an internal particle matrix of alginate;
(iii) an internal semipermeable particle coating of low molecular wieght polylysine enclosing the internal particle matrix; and
(b) a super matrix of alginate in which the internal particle (or particles) is embedded; and
(c) an outer semipermeable coating of polylysine, e.g., low molecular weight polylysine, enclosing the super matrix, the composite microreactor preferably providing a molecular weight cutoff that prevents molecules larger than about 400,000 daltons from coming into contact with the source and having an antibody which reacts with a swine antigen, e.g., a SLA class I or class II antigen, as a capture agent attached to the outer coating of polylysine.
In preferred embodiments, the capture agent is an antibody or antibody fragment, even more preferably, the capture agent is an antibody or antibody fragment which binds an antigen or epitope other than the therapeutic substance released by the source. In an even more preferred embodiment, the antibody or antibody fragment is directed against an antigen which is an MHC class I, an MHC class II, an SLA class I, or an SLA class II antigen. In another preferred embodiment, the antibody or antibody fragment is a human antibody, a humanized antibody, an antibody which is engineered to minimize host response, or an engineered binding protein of a parental protein which is preferably of human origin.
In another aspect, the invention features, providing a subject with a therapeutic substance. The method includes implanting in the subject an implantable device which includes a source of a therapeutic substance and a capture agent, e.g., an implantable device described herein.
The inventors have discovered that the inclusion of a capture agent in an extracorporeal device can be used to protect a source of a therapeutic substance in the extracorporeal device and improve the performance of the device, e.g., by extending its useful lifetime.
Accordingly, the invention features, an extracorporeal device through which is passed a host fluid, e.g., blood. (After passage through the device the host fluid is returned to the host.) The device includes a source of a therapeutic substance, e.g., an islet, and a capture agent, e.g., an antibody which binds antigens or epitopes other than the therapeutic substance released by the source. The source is separated from the host body fluid by a semipermeable component. Preferably a semi-permeable component also separates the capture agent, from the host body fluid. The capture agents should be in a different compartment than the source of a therapeutic substance, or otherwise immobilized to keep it from contacting the source of a therapeutic substance. The capture agent can, e.g., be coupled to the surface of the microreactor, or to the surface of a component of the microreactor.
In preferred embodiments, the capture agent is an antibody or antibody fragment, even more preferably, the capture agent is an antibody or antibody fragment which binds an antigen or epitope other than the therapeutic substance released by the source. In an even more preferred embodiment, the antibody or antibody fragment is directed against an antigen which is an MHC class I, an MHC class II, an SLA class I, or an SLA class II antigen. In another preferred embodiment, the antibody or antibody fragment is a human antibody, a humanized antibody, an antibody which is engineered to minimize host response, or an engineered binding protein of a parental protein which is preferably of human origin.
In preferred embodiments, the device includes a cell or tissue. The cell or tissue can be autologous, allogeneic, or xenogeneic, with regard to the subject. A xenogeneic cell or tissue can be from a species which is concordant or discordant with the subject. The cell or tissue can be from the subject, but if it is from the subject, it is preferably genetically engineered to express a substance not normally expressed by or on that cell or tissue.
In preferred embodiments, the cell or tissue is from a a dog, pig, goat, rabbit, horse, cow, or sheep, or a non-human primate species.
In preferred embodiments, the cell is a pancreatic islet cell. In preferred embodiments, the pancreatic islet is from a dog, pig, goat, rabbit, horse, cow, sheep, or a non-human primate. In particularly preferred embodiments, the pancreatic islet is from a pig. In preferred embodiments, the pancreatic islet is from a human other than the subject.
In preferred embodiments, the cell or tissue is genetically engineered.
The cell or tissue can be from the pancreas, adrenal gland, brain, kidney, liver, thymus parathyroid or thyroid. In a preferred embodiment, the cell is a cultured cell. In a preferred embodiment, the cell is from a primary culture. In a preferred embodiment, the cell has been treated with a cytokine or a growth factor.
In preferred embodiments: the cell is an immortalized cell; the cell is a blood cell; the cell or tissue is a fetal; the cell is a skin, astroglial, or myoblast cell.
In preferred embodiments the device includes a port for admitting flow of the body fluid into the device which port communicates with a chamber which encloses a source of a therapeutic substance, e.g., an islet, and a capture agent, e.g., an antibody which binds antigens or epitopes other than the therapeutic substance released by the source. The source is separated from the host fluid by a semipermeable component, and preferably, the capture agent is separated from the source by a semipermeable component. The fluid exits the device by the same port or by a second port. The device can be used in xe2x80x9cbatchxe2x80x9d or continuous flow fashion.
In preferred embodiments the semipermeable component includes the three-part composite layer described herein.
The methods of the invention allow implanting of allogeneic or xenogeneic tissue with little or no immunosuppression.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those herein can be used in the practice or testing of the present invention, the preferred methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.
Other features and advantages of the invention will be apparent from the following detailed description and from the claims.